hey observed that leaves and other light substances floated
several inches above the surface of the water in the pools. On coming
to the edge and making tests, they found a light liquid, as invisible
as air, superimposed upon the water, with sufficient buoyancy to
sustain dry wood and also some forms of life. They also observed that
insects coming close to the surface and apparently inhaling it, rapidly
increased in size and weight, from which they concluded it must throw
off nitrogen, carbon, or some other nourishment in the form of gas.
The depth upon the water was unaffected by rain, which passed through
it, but depended rather on the condition of the atmosphere, from which
it was evidently condensed. There seemed also to be a relation between
the amount of this liquid and the activity of the spirits. Finally,
when their ammunition showed signs of running low, they decided to
return to the Callisto, go in it to the other side of the planet, and
resume their investigations there. Accordingly, they set out to
retrace their steps, returning by a course a few miles to one side of
the way they had come, and making the cave their objective point.
Arriving there one evening about sunset, they pitched their camp. The
cave was sheltered and comfortable, and they made preparation for
passing the night.

"I shall be sorry," said Ayrault, as they sat near their fire, "to
leave this place without again seeing the bishop. He said we could
impress him anywhere, but it may be more difficult to do that at the
antipodes than here."

"It does seem," said Bearwarden, "as though we should be missing it in
not seeing him again, if that is possible. Nothing but a poison-storm
brought him the first time, and it is not certain that even in such an
emergency would he come again uncalled."

"I think," said Ayrault, "as none of the spirits here are malevolent,
they would warn us of danger if they could. The bishop's spirit seems
to have been the only one with sufficiently developed power to reappear
as a man. I therefore suggest that to-morrow we try to make him feel
our thought and bring him to us."

CHAPTER VII.

THE SPIRIT'S SECOND VISIT.

Accordingly, the next morning they concentrated their minds
simultaneously on the spirit, wishing with all their strength that he
should reappear.

"Whether he be far or near," said Ayrault, "he must feel that, for we
are using the entire